Thermal changes of rare earth phosphate minerals
Thermal changes of rare earth phosphate minerals
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稀土磷酸盐矿物的热变化
DOI：
10.2465/gkk1952.19.117
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发表时间：
1990
期刊：
影响因子：
--
通讯作者：
T. Nomura
中科院分区：
文献类型：
--
作者：
Y. Hikichi;Kyouhei Murayama;H. Ohsato;T. Nomura
研究了合成的稀土磷酸盐在50°C ~ 1800°C、常压或7.5 ~ 12.5GPa压力下的热变化。1)在50°C或90°C、pH=1的条件下，由R盐和正磷酸的混合溶液中沉淀法合成了RPO 4·nH 2 O（n=0.5 ~ 1.0，R=La-Gd，Tb，Dy，Y，Er，或R=Ce+Y）;在190°C至250°C下使横纹色氨酸型磷酸盐脱水。对应于nH 2 O的水是沸石水。无水RPO_4在常压空气中加热时的热变化为：（1）RPO_4（R=La-Gd或R=Ce+Y）→独居石，（2）RPO_4（R=Tb或Dy）→独居石→磷钇矿，（3）RPO_4（R=Y或Er）→磷钇矿。独居石向磷钇矿（2）的转化是单晶型的。然而，当在7.5至12.5 GPa的压力下在650°C至1000°C的空气中加热时，Xenotime型DyPO 4转变为独居石型DyPO 4。2)在50°C和pH=1的条件下，用沉淀法从R盐和正磷酸的混合溶液中合成了Weinschenkite型RPO 4·2 H2O（R=Dy，Y，Er，Yb）。温氏型RPO_4·2 H_2 O在常压下加热时逐渐转变为磷钇矿。
Thermal changes of synthesized rare earth phosphates were studied at 50°C to 1800°C in air under atmospheric pressure or the pressure of 7.5 to 12.5 GPa. 1) Rhabdophane-type RPO4·nH2O (n=0.5 to 1.0, R=La-Gd, Tb, Dy, Y, Er, or R=Ce+Y) were synthesized by precipitation from the mixed solution of R-salt and orthophosphoric acid at 50°C or 90°C and pH=1, or by grinding weinschenkite-type RPO4·2H2O (R=Dy, Y, or Er) at room temperature for 10 days. Rhabdophane-type phosphates were dehydrated at 190°C to 250°C. The water corresponding to nH2O was zeolitic water. Thermal changes of rhabdophane-type anhydrous RPO4, when heated in air under atmospheric pressure, were as follows : (1) rhabdophane-type RPO4 (R=La-Gd, or R=Ce+Y)→monazite, (2) rhabdophane-type RPO4 (R=Tb or Dy)→monazite→xenotime, (3) rhabdophane-type RPO4 (R=Y or Er)→xenotime. The transformation from monazite into xenotime (2) was monotropic when heated in air under atmospheric pressure. Xenotime-type DyPO4, however, transformed into monazite-type DyPO4 when heated at 650°C to 1000°C in air under the pressure of 7.5 to 12.5 GPa. 2) Weinschenkite-type RPO4·2H2O (R=Dy, Y, Er, or Yb) were synthesized by precipitation from the mixed solution of R-salt and orthophosphoric acid at 50°C and pH=1. Weinschenkitetype RPO4·2H2O gradually converted to xenotime when heated in air under atmosheric pressure.