Calcium Tungstate

Introduction

Name: Calcium Tungstate
Formula: CaWO₄
Molecular weight： 287.93
Density:6.06
CAS: 7790-75-2
EINECS: 232-219-4

Nature

The another name of it is artificial scheelite, a white powder with the tetragonal structure, slightly soluble in water and ammonium chloride solution, thermal decomposition in the hydrochloric acid.

It belongs to self-activated phosphors which is very effective light-emitting material in the conditions of X-rays, electron beams and ultraviolet excitation, the very important chemical raw materials.

Property

It issued at 253.7nm ultraviolet light blue fluorescence emission spectrum peak wavelength of 423nm, half the width of 120nm. It emits blue light in the cathode ray excitation; the anode voltage of 3kV, the peak wavelength of 415nm, luminous efficacy 851m/W in the cathode ray excitation.

Preparation

1. Burning the raw material of tungsten trioxide and calcium carbonate at 1070℃;
2. The reaction of sodium tungstate and calcium chloride solution;
3. The process of natural scheelite;
4. Sodium tungstate mixed with sodium sulfide, and dissolved in water, then added an aqueous solution of zinc chloride, filtered, the filtrate is treated with pure calcium chloride;
5. The reaction of calcium hydroxide or calcium oxide and tungsten hydroxide or tungsten oxide in an alkali metal hydroxide or carbonate solution.

Application

1. Used as raw material of tungsten series chemical products, mainly used in the production of ammonium paratungstate, tungsten trioxide, tungsten, iron, steel, alloy, tungsten material, tungsten wire and tungsten carbide and other tungsten products;
2. Used in fluorescent paint, photography light screen tube, medicine, X-ray photographs and fluorescent lighting. It also can be used luminous paint, fluorescent lights, neon signs, X-ray screen, medicine, scintillation counter and lasers.

Storage

sealed, and store in a cool, dry place.