Abstract: Neodymium-doped gehlenite crystal and laser using said crystal. The crystal according to the invention has the formula Ca.sub.2-x Nd.sub.x Al.sub.2+x Si.sub.1-x O.sub.7 with 0<.times..ltoreq.1. This crystal can be used as a laser emitter (4) optically pumped by a laser diode (6), whose temperature is not controlled by a Peltier element component.

Abstract: Mixed strontium and lanthanide oxides and a laser using monocrystals of these oxides.These oxides with a magnetolead type crystalline structure have the following formula:Sr.sub.x Ln1.sub.y1 Ln2.sub.y2 Ln3.sub.y3 M.sub.z A.sub.a B.sub.b O.sub.19--kin which Ln1 represents at least one trivalent element selected from lanthane, gadolinium and yttrium; Ln2 represents at least one trivalent element selected from neodymium, praseodymium, erbium, holmium and thulium; Ln3 represents an element selected from bivalent europium or trivalent cerium with retention of electric neutrality by virtue of oxygen holes; M represents at least one bivalent metal selected from magnesium, manganese and zinc; A represents at least one trivalent metal selected from aluminum and gallium; B represents a trivalent transition metal selected from chromium and titanium; x, yl, y2, y3, z, a, b and k represent numbers so that 0<x<1, 0.ltoreq.y1<1, 0<y2<1, 0.ltoreq.y3<1, 0<z<1, 10.5<a<12, 0.ltoreq.b.ltoreq.0.