Linear magnetoelastic coupling and magnetic phase diagrams of the buckled-kagomé antiferromagnet $$\hbox {Cu}_3\hbox {Bi}{(\hbox {SeO}_3)_2}\hbox {O}_2\hbox {Cl}$$ Cu 3 Bi ( SeO 3 ) 2 O 2 Cl

Single crystals of Cu $$_3$$ Bi(SeO $$_3$$ ) $$_2$$ O $$_2$$ Cl were investigated using high-resolution capacitance dilatometry in magnetic fields up to 15 T. Pronounced magnetoelastic coupling is found upon evolution of long-range antiferromagnetic order at $$T_{\mathrm {N}}$$ $$= 26.4(3)$$ K. Grüneisen analysis reveals moderate effects of uniaxial pressure on $$T_{\mathrm {N}}$$ , of 1.8(4) K/GPa, $$-0.62(15)$$ K/GPa and 0.33(10) K/GPa for $$p \parallel a$$ , b, and c, respectively. Below 22 K Grüneisen scaling fails which implies the presence of competing interactions. The structural phase transition at $$T_{\mathrm {S}}$$ $$= 120.7(5)$$ K is much more sensitive to uniaxial pressure than $$T_{\mathrm {N}}$$ , with strong effects of up to 27(3) K/GPa ( $$p \parallel c$$ ). Magnetostriction and magnetization measurements reveal a linear magnetoelastic coupling for $$B\parallel c$$ below $$T_{\mathrm {N}}$$ , as well as a mixed phase behavior above the tricritical point around 0.4 T. An analysis of the critical behavior in zero-field points to three-dimensional (3D) Ising-like magnetic ordering. In addition, the magnetic phase diagrams for fields along the main crystalline axes are reported.