生长正钒酸钙晶体Ca_3(VO_4)_2的原料制备

Composing and Processing of Ca_3(VO_4)_2 Raw Materials Used for Growth Crystals

本文报道了Ｃａ３（ＶＯ４）２ 晶体生长时原料组分的选择，指出相图上ＣａＯ质量分数的范围在３６ ％～４０％ 是合理的生长区间。讨论了合成原料的合理方式，采用ＣａＣＯ３ 与Ｖ２Ｏ５ 直接合成的方法能够避免采用ＣａＯ或Ｃａ（ＯＨ）２ 与Ｖ２Ｏ５ 进行合成时原料与空气中的Ｈ２Ｏ 及ＣＯ２ 反应，影响称量准确性的问题。详细地给出了光加热浮动熔区法和提拉法生长Ｃａ３（ＶＯ４）２ 晶体时原料的制备工艺。采用光加热浮动熔区法时用９ＭＰａ 压力制棒，采用两步法烧结：８５０ ℃×８ｈ →１２００ ℃×８ｈ。在提拉法生长晶体时采用球磨机湿混料、８０ ℃烘干、２０ＭＰａ 压力下压料饼，也采用两步法烧结：８５０℃×８ｈ →１２００ ℃×８ｈ。

s The composition of Ca 3(VO 4) 2 charge is chosen by analysis the phase diagram of V 2O 5 CaO system,It turns out that the Ca 3(VO 4) 2 crystal can be grown from the charges which composition is CaO within 36wt%～40 wt%.The most reasonable composing method is proposed by discussing the possible ones.The reaction between CaCO 3 and V 2O 5 is better than the reaction between CaO and V 2O 5 or Ca(OH) 2 and V 2O 5 for its avoiding the reaction of H 2O or CO 2 with CaO and Ca(OH) 2 that might affect the weighing accuracy.Details about the mixture,shaping and high temperature treatment of the charges are given for both light heating floating zone method and Czochralski method to growth crystal.With the light heating floating zone method,the charge rod was made under the pressure of 9MPa and heated with two steps 850℃×8h→1200℃×8h.With the Czochralski method,the charge was mixed by ball grinding mill then evaporated the alcohol at 80℃.The charge disc was made under the pressure of 20 MPa and heated with two steps 850℃×8hr→1200℃×8hr.