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 lanthanide-magnesium aluminates and lasers using monocrystals of these aluminates. These lasers in particular incorporate two flash lamps for longitudinally pumping a monocrystalline rod of a magnetoplumbito-aluminate emitting visible or infrared light, amplified between a mirror, a polarizing prism being used for passing to the outside of the laser the amplified light beam. The aluminate is of formula: (La.sub.1-x Tr.sub.x).sub.1-y-v Mg.sub.1-z-t Al.sub.11-u+y+2Z/3 Cr.sub.u O.sub.19-t-3v/3 in which Tr represents (a) at least one single trivalent substance chosen from among lanthanides, Y.sup.3+, Sc.sup.3+, or (b) at least one pair of lanthanides formed from a divalent element and a trivalent element, while retaining the electrical neutrality by adding aluminum or oxygen deficiencies, or any combination of (a) and (b); x is a number such that 0.ltoreq.x<1; y and v are numbers such that 0.ltoreq.y+v.ltoreq.0.4; z and t are numbers such that 0.ltoreq.z+t<1, provided that when z=t=O, y+v is .noteq.

Abstract: Mixed lathanum-magnesium aluminates, their production process and lasers using these aluminates.These lasers comprise two flash lamps for longitudinally pumping a bar of an aluminate of formula La.sub.1-x Nd.sub.x Mg.sub.Y Al.sub.11 O.sub.18+y, x and y being numbers such that O<x.ltoreq.0.2 and O<y<1, preferably with y ranging from 0.5 to 0.55, emitting in the infrared, mirrors for amplifying the light emitted by the bar and a polarizing prism for passing the amplified light beam outside the laser.

Abstract: Mixed lanthanide-magnesium aluminates and lasers using monocrystals of these aluminates.These lasers in particular incorporate two flash lamps for longitudinally pumping a monocrystalline rod of a magnetoplumbite-aluminate emitting visible or infrared light, amplified between a mirror, a polarizing prism being used for passing to the outside of the laser the amplified light beam. The aluminate is of formula:(La.sub.1-x Tr.sub.x).sub.1-y-v Mg.sub.1-z-t Al.sub.11-u+y+2z/3 Cr.sub.u O.sub.19-t-3v/3.in which Tr represents a) at least one single trivalent substance chosen from among lanthanides, Y.sup.3+, Sc.sup.3+, or b) at least one pair of lanthanides formed from a divalent element and a trivalent element, while retaining the electrical neutrality by adding aluminium or oxygen deficiencies, or any combination of (a) and (b); x is a number such that 0.ltoreq.x<1; y and v are numbers such that 0.ltoreq.y+v.ltoreq.0.4; z and t are numbers such that 0.ltoreq.z+t<1, provided that when z=t=0, y+v is .noteq.

Abstract: These lasers in particular have two flashlamps (30, 32) for longitudinally pumping a monocrystalline aluminate bar (28) emitting in the visible and near infrared, two mirrors (38, 40) for amplifying the light emitted by the bath, a polarizer prism (42) used for feeding the amplified light beam to the outside of the laser cavity. The magnetoplumbite-type aluminate has in particular the formula:La.sub.1-x Mg.sub.1-y-z Mt.sub.v Al.sub.11+x+2y/ 3-v O.sub.19-z(II)in which Mt represents a transition metal chosen from titanium and zirconium; x is a number such that 0<x<0.3; y and z are numbers such that 0.ltoreq.y+z.ltoreq.1 with 0.ltoreq.y.ltoreq.1 and 0.ltoreq.z.ltoreq.1; v is a number such that 0<v<1.

Abstract: A mixed aluminum oxide having the following formula:X.sup.1.sub.(x.sbsb.1.sub.-x.sbsb.2.sub.) X.sup.2.sub.(x.sbsb.2.sub.) M.sup.1.sub.(y.sbsb.1.sub.-y.sbsb.2.sub.) M.sup.2.sub.(y.sbsb.2.sub.) Al.sub.(z.sbsb.1.sub.-z.sbsb.2.sub.) M.sup.3.sub.(z.sbsb.2.sub.) O.sub.19wherein X.sup.1 and X.sup.2, which can be the same or different, represent a metal selected from the group consisting of lanthanum, praseodymium, neodymium, samarium and gadolinium, provided that X.sup.1 and X.sup.2 are different when X.sup.1 or X.sup.2 represents lanthanum or gadolinium; M.sup.1 and M.sup.2, which can be the same or different, each represent a metal selected from the group consisting of magnesium and divalent transition metals; M.sup.3 represents a trivalent transition metal; x.sub.1 represents a number from 0.8 to 1; y.sub.1 represents a number from 0.7 to 1; z.sub.1 represents a number from 10 to 12; x.sub.2 represents a number from 0 to x.sub.1 ; y.sub.2 represents a number from 0 to y.sub.1 ; and z.sub.