Spherical calcium tungstate microcrystals were prepared with heat treatment at 100 ℃ and using a calcium tungstate muddy solution by precipitation with natrium tungstate and calcium nitrate as starting materials, and with cetyltrimethyl ammonium bromide as a surfactant. The spherical calcium tungstate microcrystals were characterized by X-ray diffraction and transmission elec-tron microscopy. The results indicate that the crystallites of the calcium tungstate samples are excellent, and the diameters of the calcium tungstate microcrystals with outstanding spherical morphology are 2.1-3.2 μm, and the particles are well dispersed and not aggregated. Cetyltrimethyl ammonium bromide plays an important role in the formation of spherical calcium tungstate microcrystals. When excited at 265 nm, the luminescence of calcium tungstate microcrystals exhibits a luminous peak in the blue band. The luminescent intensity of spherical calcium tungstate microcrystals is about two times greater than that of the aggregate particles.

 

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Calcium tungstate nanocrystalline was successfully synthesised via a microwave irradiation method using Ca(NO₃)₂ and Na₂WO₄ in ethylene glycol, without the requirement of any calcination. The product was analysed by X-ray diffraction (XRD), Raman spectroscopy, Fourier transform infrared spectroscopy (FTIR), transmission electron microscopy (TEM), selected area electron diffraction (SAED) and photoluminescence spectrometry. XRD, SAED and TEM revealed that the product was body-centred tetragonal CaWO₄ with an average particle size of 12 nm. Different oscillation modes were detected by Raman spectroscopy and FTIR. They showed the strong W–O stretching in [WO₄]²⁻ tetrahedrons at 711–933 cm⁻¹. Photoluminescence (PL) of CaWO₄ nanocrystalline showed the maximum emission peak at 422 nm.

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There is a facile microemulsion-mediated hydrothermal procedure to synthesize the precursor of Eu³⁺-doped CaWO₄ nanoparticles.SEM shows that the nanoparticles are similar to sphere.The Eu³⁺-doped CaWO₄ phosphor was characterized by powder X-ray diffractometer.According to our measurements with XRD,the products belong to tetragonal structure.The effects of sintering temperature and time on the luminescence of the samples were investigated.The luminescence data indicate the optimum condition for heat-treatment of the precursor was at 600℃ for 2h.The effects of different content of Eu³⁺ on the luminescence of CaWO₄∶Eu³⁺ nanoparticles were also investigated,and the results display that luminescence intensity is enhanced with the slightly increasing of Eu³⁺ content,the optimum of Eu³⁺-doped concentration is 0.1 %(mole fraction).

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The role of defects formed owing to the deviations from stoichiometry is analyzed for CaWO₄ single crystals grown by the Czochralski method. It is shown that the defects leading to the light scattering in CaWO₄ crystals affect the spectra of X-ray luminescence and the luminescence kinetics only slightly, but give rise to an additional peak in the thermoluminescence spectrum. Addition of WO₃ to the melt eliminates the light scattering and the additional thermoluminescence peak.

 

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The seven independent adiabatic elastic constants of CaWO₄ are calculated using Born's longwave method and the rigid ion model of Steinman et al. (1972). Good agreement exists between the calculated elastic constants and those measured by Gluyas et al. (1973). The sign of C₁₆ is consistent with the observation of Farley et al. (1972). Further the dynamical equilibrium conditions are also found to be satisfied for this model.

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The e.p.r. spectrum of (ReO₄)O^2- in CaWO₄ has been measured in the temperature 4-120 K as a function of orientation. The spectrum including many forbidden lines may be fitted to the spin Hamiltonian H = μ _BB\cdot g\cdot S\cdot +I\cdot tilde{A}\cdot S\cdot +I\cdot tilde{P}\cdot I\cdot in tetragonal form with S = 1/2 and I=5/2. At 4.2 K, endor measurements for the magnetic field oriented parallel to the unique axis, taken in conjunction with the e.p.r. spectrum, yield spin Hamiltonian parameters g_\| = 1.8549 ± 0.0002, g_perp = 1.7164 ± 0.0002, A_perp = (±)(42± 2)× 10^-4 cm ^-1, A_perp = (±)(324± 2)× 10^-4 cm ^-1 and P_\| = (mp)(5± 3)× 10^-4 cm ^-1, with g_N = (±) 1.27 for the ¹⁸⁷Re nuclide. These parameters are consistent with the single electron occupying the |3z² - r²> orbital of a 5d¹ ion. The e.p.r. linewidth, which is strongly sensitive to both orientation and temperature, has been examined in detail. Preliminary studies of the relaxation properties of the centre are discussed in qualitative terms.

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The energy levels of the 4I ground term of Er³⁺ in single crystals of CaWO₄ were established by absorption and fluorescence spectra measurements. The measurements were made using crystals at temperatures of 2, 20, and 85°K. The energy level scheme allows an interpretation of the 1.612‐μ four‐level CaWO₄:Er³⁺ laser transition and shows the terminal energy level of this transition to be 318 cm⁻¹ above the ground state rather than 375 cm⁻¹ as reported by Kiss and Duncan. An effective Hamiltonian of the form suggested by Karayianis was diagonalized in a basis of Russell–Saunders wavefunctions to obtain the calculated energy levels and wavefunctions for the entire ground term of Er³⁺. The calculation takes into account the complete J mixing of the states within the ground term and is equivalent to determining the effects of the spin–orbit interaction to better than second order. An rms deviation of 18 cm⁻¹was found as the best agreement between the calculated and experimental energy levels using the Hamiltonian: H = λ1(L⋅S) + λ2(L⋅S)2 + λ3(L⋅S)3 + ΣlmB†lmClm. The empirically determined parameters are (in cm⁻¹) λ1 = − 613, λ2 = − 19.3, λ3 = − 0.499, B20 = 404, B40 = − 685, B60 = 12.4, B44 = 728,ReB64 = 452, and ImB64 = 164. Using wavefunctions determined with these parameters, the g factors were calculated for the states of the ground term. The calculated and measured g factors for the two lower energy states are in good agreement where the calculated values are g‖(ground state) = 1.265, g⊥(ground state) = 8.487, g‖* (first excited state) = 3.22, and g⊥* (first excited state) = 7.06, and the measured values in the same order are g‖ = 1.247, g⊥ = 8.400, g‖* = 3.42, and g⊥* = 6.98. A Γ5,6ground statewavefunction is compatible with the results obtained here, whereas a Γ7,8ground statewavefunction is not. Previous studies had not established the ground statewavefunction uniquely.

 

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Tungsten is an extremely dense metal, heavier than lead. It is also very durable, so a high-density tungsten dart resists wear and the grip will last much longer. On softer metal darts, the grooves and rough knurling may wear down fairly quickly from skin acid, friction, and hitting other darts. Originally tungsten was only a small percentage of the dart barrel (40 - 50%), today most tungsten darts are between 80 and 95% tungsten.

Today let’s learn some glossaries of tungsten dart from R to X!

-R-
REDEEMER - A dart, (often a T20) that "redeems" two previous poor efforts.

RIGHT CHURCH - Term for hitting a double or triple, but the wrong number. Also known as "DADDY'S BED"

ROBIN HOOD - When you shoot a dart into the shaft of another.

ROUND OF NINE - Throwing three triples in one turn in Cricket.

ROUND THE CLOCK - Any of a number of game variants where players compete to be the first to hit all the sectors on the dartboard in an agreed order (usually numerical), finishing with the outer bull followed by the bull. In some versions hitting a double entitles the player to skip the next number, with a treble entitling the player to skip two numbers. Also commonly played by single players as a form of practice.

-S-
SCROAT - A dart that is aimed for treble 20, but ends up in double 20.

SET - A scoring method used in many tournaments.

SHAFT - The middle section of the darts that holds the Flight.

SHANGHAI - A score of a single, double and triple in the same number. "Shanghai" sometimes refers to a checkout of 120 (single, treble and double 20, also as "Shanghai 20"). In some games this is an automatic win. This is also the name of a game.

SHARKEY - A non-registered player who has to assume a false identity in order to fill in for an absent player in a league game, e.g. "due to poor turnout, The Arms had to use a Sharkey".

SHUT OUT - When you lose a game without ever scoring in it.

SINGLE BULL - On dartboards configured with a bullseye consisting of two concentric circles, the outer circle is commonly green and worth 25 and the inner circle is commonly red and worth 50 points. Hitting the outermost ring of this type of bullseye is a "SINGLE-BULL". (See also: "BULLSEYE")

SKUNKED - When you lose a game without ever scoring in it.

SLOP - Darts that score, but not where you wanted them.

SPIDER - The metal web that divides the dartboard into sections.

SPLASH - Darts that score, but not where you wanted them.

SPRAY 'N' PRAY - Darts thrown by an irate and less talented player, rather quickly

STICKS - The darts themselves.

STRAIGHT IN - A game that requires no special shot to begin scoring.

STRIKING OIL - Hitting a double bull when 'diddling for the middle' - comes from the black centre of some modern dart boards.

-T-
THREE IN A BED - Three darts in the same triple of a number. i.e. three triple 20's 180!

THROW LINE - The line you stand behind and throw the darts from.

TOE LINE - The line you stand behind and throw the darts from.

TON - A score of 100 in a game of x01. Scores over 100 would be called a "ton-whatever" for example, a ton-thirty would be a score of 130.

TON OF NAILS - A score of 5 where all three darts fell in the 1 bed with 1 dart in the treble 1.

TOP BANANA - Double 20. Usually exclaimed after hitting this bed to win a match.

TOP OF THE BOARD - The numbers on the top half of the dartboard.

TOPS - The double 20 bed. As in "he wants tops for the match".

TRIPLE/TREBLE - The thin inner ring of the dartboard, it usually counts for three times the number hit.

-U-
UPSTAIRS - The upper half of the dartboard

-W-
WET FEET - Standing too close to the dartboard (that is, in front of the toe line).

WEDGE - A section or sections of the dartboard.

WHITE HORSE - Scoring three virgin (untouched) triples in Cricket.

WIRE - Darts that just miss where you aimed but on the other side of the spider.

-X-
X - A double-one out

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Tungsten is an extremely dense metal, heavier than lead. It is also very durable, so a high-density tungsten dart resists wear and the grip will last much longer. On softer metal darts, the grooves and rough knurling may wear down fairly quickly from skin acid, friction, and hitting other darts. Originally tungsten was only a small percentage of the dart barrel (40 - 50%), today most tungsten darts are between 80 and 95% tungsten.

Today let’s learn some glossaries of tungsten dart from H to P!

-H-
HAT TRICK - A score of three bullseyes.

HIGH TON - A score greater than 150.

HOCKEY - A raised 1 1/2" board used to mark the throwing line.

-I-
INNING - A round of completed turns by both players, or a turn in a particular game that has innings, like Baseball or Shanghai.

-L-
LEG - A game in a match, as in "the best of five legs", in which each leg is an entire game. Or, in the game of Legs, a stripe on the dartboard.

-M-
MAD HOUSE - The double-1. At least two explanations for the term have been proffered; because it can drive you crazy trying to hit one in a game of x01, or because it impossible to "get out" of the mad house - once a player has a score of 2 the only way to finish the game is by hitting a double-1.

MAXIMUM - A score of 180

MAXIMUM CHECK-OUT - A score of 170 to end a game. treble-20, treble-20, inner bull

MUGS AWAY - Loser of the previous game goes first in the next game.

MURPHY - A score of single-5, single-20, single-1 in a game of x01. Based on Murphy's Law.

-N-
NAIL - Another word for 1. See "Bucket of Nails" and "Ton of Nails".

NINE DARTER - When a player completes a game of 501 in the minimum required nine-darts. This is a very rare event. There is usually a cash prize for professionals throwing a televised nine-darter.

NOT OLD - A score of 37 (usually by hitting a 20, a 5 and a 12). The phrase is believed to have its origins in a Monty Python sketch.

-O-
OCHE - The line you stand behind and throw the darts from.

-P-
PERFECT SCORE - When a player scores a maximum 180 points in one throw of three darts.

PERFECT FINISH - When a player finishes a game with a maximum score of 170. This must be done by scoring treble 20, treble 20, double bull, with only three darts. This is considerably more difficult than hitting a perfect score as the player must break focus to change targets and it can only be done if the player has an exact score of 170 remaining.

PIE - any of the numbered segments on the dartboard.

POPCORN - When the darts land so close to each other, they knock their flights out.

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Tungsten is an extremely dense metal, heavier than lead. It is also very durable, so a high-density tungsten dart resists wear and the grip will last much longer. On softer metal darts, the grooves and rough knurling may wear down fairly quickly from skin acid, friction, and hitting other darts. Originally tungsten was only a small percentage of the dart barrel (40 - 50%), today most tungsten darts are between 80 and 95% tungsten.

Today let’s learn some glossaries of tungsten dart from A to G!

-A-
ANNIE'S ROOM - The number One (1).

ARROWS - Another term for darts.

ARCHER - Refers to a player who throws very quick smooth darts

-B-
BABY TON - A score of 95, usually by scoring five 19s.

BAG O' NUTS - A score of 45.

BARREL - The metal body of the darts where they are gripped.

BASEMENT - The double-3.

BOTTOM OF THE BOARD - The numbers on the bottom half of the dartboard.

BOUNCE OUT - When a dart hits a wire on the board flush-on and bounces back off the dartboard. Can be potentially dangerous to spectators who are too close.

BREAKFAST - (or BED 'N' BREAKFAST) A score of 26, made up of a single-5, single-20, single-1 in a game of x01. This is a common score in darts because players aiming for the 20 sector (which contains the highest scoring area on the dartboard) will often accidentally hit the 1 and the 5 sectors, which are located on either side of the 20. The term comes from the typical price of a bed-and-breakfast in times gone by: 2 shillings and sixpence, or "two and six". (See also "CHIPS")

BUCKET/BAG OF NAILS - Landing all three darts in the 1s.

BUCKSHOT - A throw when darts land wildly all over the dartboard.

BULL-OFF - See DIDDLE FOR THE MIDDLE.

BULLSEYE (or BULL) - The bull's eye, which has an Outer Bull and an Inner Bull.

BUST - Hitting more than you needed in an x01 game. The darts do not count and the player begins his next turn on the same score he had prior to.

-C-
CRICKET - In a Cricket game this refers to high scores base on the number of darts scored. For example a triple-20, single-20, single-20 would be called a C-5 because "5 darts" were scored with three darts .
CHAMPAGNE BREAKFAST - Hitting treble 20, treble 1 and treble 5 in three darts (see "BREAKFAST")

CHIPS - A score of 26. (See also: "BREAKFAST")

CHUCKER - A player who just "chucks" the darts at the board, doesn't aim or care.


CIRCLE IT - When a player scores a single digit (less than 10) with three darts, his team-mates would shout out "Circle it!" to the scorekeeper to highlight the terrible throw. A variation on this tradition is to draw a fish around the score, often leading to aquarium-related jokes being aimed at particularly poor or unlucky players.

CLOCK - The dartboard itself, usually in the context of "ROUND THE CLOCK".

CORK - The center of the dartboard. This comes from the cork in the end of a keg where it is tapped. The ends of kegs were used for targets in the game's early days.
COVER - A term frequently used by Sid Wadell, meaning aiming for treble 19.

-D-
DAIRYLEA DARTS - A throw that is 'spread' around the board, named after the cheese spread Dairylea.

DEVIL - The treble-6, so called due to '666', and the fact that it is often hit in error when going for treble-13 or treble-10.

DIDDLE FOR THE MIDDLE - A throw to see who gets one dart closer to the bullseye to determine who throws first in the game. Also known as a "BULL OFF", "MIDDLE FOR MIDDLE" and "OUT FOR BULL".

DOUBLE - The thin outer ring of the dartboard. In standard x01 games, a double counts for two times the number hit.

DOUBLE-BULL - On dartboards configured with a bullseye consisting of two concentric circles, the outer circle is commonly green and worth 25 and the inner circle is commonly red and worth 50 points. Hitting the innermost ring of this type of bullseye is a "DOUBLE-BULL". (See also: "BULLSEYE")

DOUBLE IN - A variant of x01 in which a double is needed to start the game.

DOUBLE TOP - The double 20.

DOUBLE TROUBLE - Not being able to hit the double needed to win the game.

DOWNSTAIRS - The lower portion of the dartboard, usually in reference to the 19s in a game of x01.

-E-
EASY IN - A game that requires no special shot to begin scoring.

EDDIE SHUFFLE - The art of adjusting ones stance or position along the ockey in an attempt to circumnavigate a troublesome 'blocking' dart. Also referred to as The Milk Float.

-F-
FEATHERS -The number 33.

FOGLE - A series of castaway darts thrown with no other purpose than to irritate opponents.

FLIGHTS - The "feathers" of the dart that give it aerodynamic float. Also known as wings.

-G-
GAME ON - Advises all players that the match has now started

GAME SHOT - Signifies that the match winning double has been hit

GRANNY - A lose without scoring, see SHUT OUT

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