The high-pressure behavior of wardite, NaAl₃(PO₄)₂(OH)₄·2H₂O (a = 7.0673(2) Å, c = 19.193(9) Å, Sp. Gr. P4₁2₁2), has been investigated by in-situ single-crystal synchrotron diffraction experiments up to 9 GPa, using a diamond anvil cell under quasi-hydrostatic conditions. This phosphate does not experience any pressure-induced phase transition, or anomalous compressional behavior, within the pressure-range investigated: its compressional behavior is fully elastic and all the deformation mechanisms, at the atomic scale, are reversible upon decompression. A second-order Birch–Murnaghan Equation of State was fitted to the experimental data, weighted by their uncertainty in pressure (P) and volume (V), with the following refined parameters: V₀ = 957.8(2) ų and K_V0 = −V₀( ¶P/¶V)_P0,_T0 = 85.8(4) GPa (β_V0 = 1/K_V0 = 0.01166(5) GPa⁻¹). Axial bulk moduli were also calculated, with: K₀(a) = 98(3) GPa (β_0(a) = 0.0034(1) GPa⁻¹) and K₀(c) = 64(1) GPa (β_0(c) = 0.0052(1) GPa⁻¹). The anisotropic compressional scheme is: K₀(a):K₀(c) = 1.53:1. A series of structure refinements were performed on the basis of the intensity data collected in compression and decompression. The mechanisms at the atomic scale, responsible for the structure anisotropy of wardite, are discussed.

中文翻译：

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高压下的钠钙铝石（NaAl3（PO4）2（OH）4·2H2O）：压缩行为和结构演变

wardite的高压行为，NaAl ₃（PO ₄）₂（OH）₄ ·2H ₂ O（一= 7.0673（2）埃，c ^ = 19.193（9）埃，比重= P 4 ₁ 2 ₁2），已在准静压条件下使用金刚石砧盒通过高达9 GPa的原位单晶同步加速器衍射实验进行了研究。在所研究的压力范围内，该磷酸盐没有经历任何由压力引起的相变或异常的压缩行为：其压缩行为是完全弹性的，并且在减压下，所有原子级的变形机制都是可逆的。状态的二阶桦木-Murnaghan状态方程拟合实验数据，可以通过不确定性在压力（加权P）和体积（V），用下面的精制参数：V ₀ = 957.8（2）埃³和ķ _V0 = -V₀（¶ P /¶ V）_P0，_T0 = 85.8（4）GPA（β _V0 = 1 / ķ _V0 = 0.01166（5）GPA ^-1）。轴向体积弹性模量也计算，具有：ķ ₀（一）= 98（3）GPA（β _0的（a） = 0.0034（1）GPA ^-1）和ķ ₀（C ^）= 64（1）GPA（β _{0 （c）}＝ 0.0052（1）GPa ^-1）。各向异性压缩方案为：K ₀（a）：K ₀（c）= 1.53：1。基于压缩和解压缩中收集的强度数据进行了一系列结构改进。讨论了原子级的机制，该机制负责方铁矿的结构各向异性。