FR2718567A1 - Manufacture of thin layer powdered ferroelectric cathode - Google Patents

Abstract

The ferroelectric material may be lead lanthanum zirconium titanate, PLZT, crushed to about 1 to 100 micrometres and the binder may be perspex dissolved in chloroform. The ferroelectric layer (FE) may be applied the conducting layer (RE) by rolling or plastering or by immersing the conducting layer in the ferroelectric material. The covering electrode (GE) comprises a grid, bands or holes. It is formed by vapour deposition across masks or by printing or silk-screen printing. Above this electrode is an anode (ZE), separated by a space containing a vacuum, gas or plasma. The conducting material may be made tubular allowing for ferroelectric deposition on both sides.

Description

I) FS; C R i PTION ('atlhode ferro (' lc (triqîuic i) iir la prolduhction

  ed'ée ('c-ons t sol process ic fabl) ricationI The invention relates to the simple and inexpensive manufacture of a source (of electron beams and

  more particularly: i, t of a callhodc fcrr, electriq (lle qui. au olloen cld'excitation repétif av (cc dcs imll-

  sionr (the current (of high intensity in the field lower than a microscconlde, pecut emneler on one large surfacc (the currents of electronq intensive in the surrounding environment, which can be (read gas, plasma or vacuum. I a production (of beams of (pulsed electrons. it uses ferroelectric crystals or ceramics has been described in detail in dimanides (the patents I'R - 2.639. 1511, I) 1: - 3.833.604 and Fl - 0) 42R R52

  A2. as well as in the documents. (Jundel Il. Ricge, I: ... N. Wilson .. 1. Ilanderek and K. Zioutas, I'er-

  roeleclt:; ics 1f00 (I19RQ9) p. 1-16. and he. Riegc, NIM in lPh-s. Researcih Ai 340 (1994) p. 80-8q. The radius of action of these methods (the emission of the conicric (the numerous fields of application (the techniques (the conventional emission and exceeds many part of the conventional possibilities). The main advantages are, besides makes it (eimlcnt high of electrons, the simple handling decs cathodes fe, 'roélcctl-iqlie rbhustcs d ,, is d (conditions such as compatibility with surrounding atmospheres (gas o (ut (plasma av;, nt a high ambient temperature, without heating (the cathode ellc-memer is not necessary, or such that the easy release of the emission by means of high voltage pulses (the

  low amplitude. of laser illumination or mechanical pressure pulses.

  All the ferroelectric cathodes described to date have been produced in the form (milanese plates from bars made of monocrystalline material or of nolycrystalline ceramic material sintered more or less romogXt:. Realizations of thin layers by (the proc (edés of ( thin films of colalities 0 have also produced satisfactory results.

  qunality (the long duration of the sie and of capacity of high etiqsioln.I 'however, the production of (the cathodcs fer-

  roêlcctriques according to (Cs deLiX processes s; t r, '' tres (P'olotuse. For (the numerous applications. pauliculi (-

  reimenit those o de ga (lades surFices (cathodes are necessary, Uln protcédé (Ie manufacturing less co-

  teux and simpler is desirable-

  I es inl (olvninenits es ctIhodes ferroésectriuldes existalites, namely a costly manufacturing partic (ll-

  lieierilelit lpolire large emitted surfaces (es, are removed by the present invention. It can be considered as something like the "cathode (hi poor". In addition. it combines with a simple fahbricatinm a large (emission capacity at low excitation voltages of the order of hundreds (volts

  depending on the thickness and the comp <ositionI (the cathodce.

  The object of the present invention is therefore the implementation of an inexpensive ferroelectric cathode cathode

  with large emission capacity I which can be manufactured with very simple techniques.

  These requirements are met by tuc catlhodc 'rro-oleclcctrique consisting of a first layer

  dluctrice, at least one thin layer of fcr-roelectric material. to have at least one arrangement Id elcc-

  partially electronically transmitting trode and at least one receiving electrode.

  According to the invention, the ferroelcctri cathode (which is manufactured according to my process (comprising the following steps: mn mnaterial e r.oé1ectrique is brové to obtain uerc powder f grains Ill'd, page 2

  * the hrov fcrroelectriquic malteriau is minelanLé with a binder to obtain a fcrroélec- mix

  lri (qilc before unle conistance ltC slenbl; lc; i a palte.

  * the melcoCgC fcrroéletri (lqtie is applied on at least one side (ic the conductive layer to form a layer cr fcrroclecttlique. and * the arrangement (of lcctlrodc parliellcincnt tansmciciron of electrons is fixedc on the layer fcrroélcccc-triquc.

  In a particular embodiment of the invention, the 6 steps of applying the cold coat

  side and to fix the electrode arrangement are cffcctued on the two sides of the conductive layer. he

  it is thus possible to produce three-cylinder cylindrical systems for example.

  Advantageously, the application of the ferroelectric layer is carried out by mechanical laminating or by induction with a defined thick thickness. (These two methods are much simpler and less costly than thin film methods, such as, for example, vaporization or application by spraying or by (VD) (idéposition cn gaseous phase by chemical process). other mode (ldc advantageous embodiment. the application of the cco cmhe ferroelectri (leic is cffectue by immnersion of the

  conductive layer in the liquid fcr-roelctric mixture. It is thus possible to coat the layer

  conductive simullanémlcnilt on both sides avcc d (the layers fcrroélcctriqucs.

  According to a mode (the real: ation particlier (the invention the fixing (the fixing of electroctrodc by-

  tlllllllow trallsnmettcir of electrons on the fert-electrified layer is effected by vaporization with travelrs (the adapted masks; 'the firmne (the electrode). The advantage of this writing is the weak

  mechanical stresses (the thermal side of the ferroelectric layer.

  l) in another embodiment of the invention. fixing the partial electrode arrangement

  The electron transmitter on the ferroelectric layer is done by screen printing. (e process is simpler than vaporization, but the ferroelectric layer must assimilate the thermal tensions

  appearing during the final thermal trail without flaking off the conductive layer.

  Advantageously, the electrical material used is (lead titanate or titanate dc

  lead it; ithamiuin-zirc (niunl (PI ZTI), cete classc dc fcrroélcctriqucs presenting (the valcurs of polarisa-

  tioin spoîtlan'ée particularly electedécs. Nlais the use of Other ferroelectric materials nr ', st pwa Àcluc. The ferroelectric powder can be obtained by grinding ceramics (of such materials the small size; grain size (the powder having to be between I pin and (. I min. ('Binder omrme for the cryo powder (electric, can advantageously use dissolved plexiglass

  (lans (lu chloroform. cc last can; aisencent trc evaporated by heating d (lu device.

  According to the present invention. (St (otc proposed uitelC catho (lde ferroelectric consisting of a first conductive layer. Of; i less than llii cost lic thin dc roelectric material. Of at least one arrangement of partial electrodeenmenit transmitteltr of electrons and at least a reception clectrode, the cathode

  being characterized what the festoelctlriqlc cover is made of a mixture of ferroelectrical material

  trique pulverisé et ed'tn li; an DCeux modes le the realization le la pr (ecnlt ('iventioil will now be described (written in the following description, title of xcmples nonlimiting. cli refer to the (attached drawings, on Icquels :

  Figure I schematically represents a cathode according to a first mode (the realization of the

ciîtion, ct

  Figure 2 shows schematically titc cathiode scli titi nsecolid model (the realization (lc il-

ve'ltitI o.

p:, ec 3

  i at the cathode shown on the lig is made up of a flat conductive layer RE, by exaptill) lc UIe Clecitrodc d (the base, which can have a form (tluC (lclquce Ct which is made Cil A material COl (illc-

  (Cur, ItelC quc (la la tiec mctallique par cxcnmple. On a dics c6ités dlc citte conductive layer RF ,. Ic the upper side in Fig. 1, cst applies a thin layer frrroélcctriquc I 1 '. According to I invention, ceCttC layer crcrroélcctriqtie '[T sc is composed of a necreator fcrroélcclriqic brovc in the form (the fine grain powder tcl (Im binder organic or atoirganlliqie non-conductive. As froelectric material, one uses avait- tageuscinecnt lead titanate or PU ZTI (titrate of lead-lantanium-zirconiunm), which have the same values (ie spontaneous polarization) and which can easily be bhoyis from said ceramic materials to form a louse (fine grain drc. Medium size d (grains should ltre10 inféricur i approximately Il 1 min, so that I homogeneity d (the ferroelctct layer (which is guaranteed, but nc

  should not be less than about I / in., to ensure the formation (the fecrroelectric phase.

  I c liani peuit î'rc for example plexiglass (diissout in d u (l chloroformc. I a ferioelectri powder (lil (

  cit le liantl are m (Iblan. c- (It ma lir oi <, gilc to get a frroéulcctrique mllange having a cone -

  similar resistance to a pilc .. \ near applicnlion (of this cold mixture (luc on the condicictc layer RF-, which could for example be obitenr by leîîîîillage (read by cnduction with ulle thickness d (lhnie.

  solvanit. it is to read chloroformnc in our excmple, it is easily evaporated by heating A - / \ vttu-

  tagcuscmenit the RI condulctlricc couchc also performs: be immersed in the ferroelectric mixture. spoke

  (laditcle couchlc law (conductor Rl csl cndiite simultanémcelt des dcux cotes with such couchc fcrio-

  However, the other aforementioned application methods are also suitable for ime

  application of ferroelectric melanlgc on both sides (the conductive layer (RI).

  On the 1: 1 electrocoating layer is fixed an electrode arrangement G (I. This is done for example by vaporization, by cathodic spraying or by screen printing on the emitting side of the electrocoating layer 11, according to the invention, GE electrode arrangement is partially transmctintcur

  for the electrons to be emitted and is by examnple produced in the form of a grid with bands or with holes.

  I: acc to the emmetric surface (the ferroelectric layer Fl, it is to d (read opposite the arrangement of 1cc-

  trode GiF, is arranged uCe -lccirolc dc (the reception Z; '1 (Anode) by which the transmitter circuit is electrically closed. the eleclrode dlc técc) ptio ZI: 1 is separated by the' a'angemnt of eleccitrode GF 'by a volilinc in Icqucl the cathode emits ldcs'' le'rous. ('c vluinc, cult avantaeetcsement contain a vacuum, says

gas or plasma.

  In Figure 2 csl shows a second mO (of (the realization (the invcnltion, dJans which cathode cst ar'ange dants, meu c (ifaxation coaxialc céidC ytriquc a tr (ois tlubhes. I e central tube. Cos- titillated with the coding layer RIL, is able to respccti \ ially have it inside and outside with uc u l ((ouche fcrroélectric emettclricc I :: ct [J1: 2. which testify chlactiie (leq electrons rcspcctivemneit on the lube 'interior, it is to (read the elecitrode (l of reception Z7 I. and on the external tube. ie the receiving electrode Zl: 2. I arrngeicnt rcmnfme * leCx volumnes. which are first filled with inert gases, which can be differentiated and which after ioiis; qtioi by beams of emitted electrons, can be illicit: i chiiiiqîles reactions by iincrinédiaic d ('ouivcrituircs d (the bond in the system (the tube. Instead of

  pressurized gas quclconquc, cl svstlmc i- Clut also to be filled with plasma.

  I cs gods mo (of realaiolis arel ba'és on the fact. That. During the functioning of emission with

  uni rate d (petition raised. large quantities of gas can be activated and reacted in ch'-

  culanit through these s \ stemes. However, he is in Unoteî. q, 'due to the length of clcmini lilbrc of the electrons de-bonded; cl ctii le the pressure of the gas. the electrics had kinetic energy, the amplitude order <the impulses <the voltageL used to excite the emission, the optimization of the chemical reaction processes requires Ic control dc preccion and dc pass gas velocity, as well as the choice

  adequate (lec the distance between the receiver lcctrodc; F ct the electrode arrangement (GiE.

  You must also notcr. for the use of emission surfaces (ie the size of a few

  taines d (c cmi2 up to mn2, ilcctri encrgics (qles primaries, particularly the powers of iipmul-

  sions of very high excilation must be very louirnics I) such impulses of (high power pecuvelt ctIe produced by lc montagc cni parnllcl ic leIi icurs pctils generatecus of impulse having impedancc

  low or by special SC pulse generators, î high power and high current before impec

(bass lance.

  ID) in both modes (ldc ralisalio. Have been described as a flat cathode, emulsion eminic c6té c trune calihode emitting cllindrique (lecs deux (otés. It csl alir. Quc catlhode according to the invention can adoptcr for anymcc whatever) It could for example be convex, concave, or spherical and eniettric in

  all cases either uiniquiciicilmnt on one side, or on both sides.

page 5

Claims (10)

  I. Proc (edé (i e manufacture of a ferroelectric cathode, constitce of a first layer con-   conductive (Ri). at least one thin layer of froelectric material (F,), at least one   electrode arrangement ((il) partially transmitted by electrons and at least one electron reception trode (7Z,).   characterized by the following stages: - baking a ferroelectric material to obtain a fine-grained powder,   - mix the crushed ferroelectric material with a binder to obtain a mixed fcr-   ceramic before a consistency similar to a pite, - apply the ferroelectric mixture on at least one side of the conductive layer (RF,) to form a fecrroelectric layer (F1), - fix an electrode arrangement ((it) partially transmitting electrons on the ferroelcct liquc layer (1: 1).   2. Method dc (manufacture of a ferroelectric cathode according to claim 1, in which the steps of applying the electro-electric layer (EU) and of fixing the electrode arrangement (GE)   are performed on both sides of the conductive layer (R>,).   3. Method (of manufacturing of ferroelectric cathode oil according to the standard I or the revcndica-   tion 2, in which the step of applying the electro-electric layer (: 1.) is carried out by rolling or by enductiotn.   4. Method of manufacturing a ferroelectric cathode according to claim I or the claim   tion 2, in which the step of applying the ferroelectric layer (: E) is carried out by immersing   the conductive layer (RE) in the ferroelectric mixture.   5. Method (the manufacture of a hydroelectric cathode according to any one of claims   previous. dtlan which the step (fix the electrode arrangement (GI.) partially transmitted-   electron on the iron coating (the electric (FE) is charged by vaporization through ? 5 masks.   6. Method (the manufacture of a fcr-iélcctrique cathode according to any one of claims   I to 4, in which the step (fix the electrode arrangement (GE) partially transmitting   of electrons on the ferroelectric layer (1U ') is effected by printing or by screen printing.   7. Method (flhbrication of a ferroelectric method according to any one of the returns   previous, in which the ferroelectric material is (read titanate (ldc lead or PI ZT (tita-   nate dce plonb-lanthanilin-zirconium).   8. Method for the habrication of a hydroelectric cathode according to any one of the claims   previous, in which the average size (the grains of the crushed ferroelectric material is   included cntre about I ni C't lenviron t. I mm.   9. Method (fablhrication (the third cathode-cathode according to any one of the claims   previous. in which the binder is plexiglass dissolved in chloroform.   10. (Froelectric cathode consisting of a first conductive layer (RE) of at least one thin layer of ferroelectric material (FU), of at least one electrode arrangement (Eil)   partially transmitting electrons ct (at least one receiving electrode (7ZE), caiacteri-   sce Cen cc quc the ferroelectric layer (11E) consists of a mixture of freelectric material sprayed stick and a binder.