T 0160/98 12-12-2001

Reasons for the Decision

1. Admissibility of the appeal

The respondent (patent proprietor) had submitted that the appeal was not admissible because it did not specify the extent to which amendment or cancellation of the contested decision was requested, as required by Rule 64(b) EPC.

The Board, in the communication accompanying the summons to the oral proceedings, pointed out that the notice of appeal met the requirements of Rule 64 EPC, and that the appeal was therefore admissible.

In his last letter, filed on 3 December 2001, the respondent declared that he did not wish any more to contest the admissibility of the appeal. The issue of admissibility of the appeal therefore does not require any further discussion and the appeal is admissible.

2. Admissibility of the requests of the respondent

The appellant objected that, since the requests of the respondent had not been filed within the time limit of one month before the oral proceedings mentioned in the communication of the Board, these requests were not filed in due time and were not admissible.

However, these new requests address objections expressed in the Board's communication and they do not contain any new matter with respect to the former request. Therefore, the Board, in the exercise of its discretion under Article 114(2) EPC, admits them into the proceedings.

3. Main request and the auxiliary request 1

Claim 1 of the main request concerns a superconductive oxide material which substantially consists of a single phase ABiCuO, where A is a mixture of:

(1) Ca and Sr and at least one of Mg and Ba, or

(2) Ca and Sr,

the ABiCuO forming a crystal phase in which the atomic ratio of A/Bi/Cu is substantially 3/2/2 and the material having a superconductive transition temperature above 80 K.

In contrast to claim 1 of the main request, component A of the superconductive material of claim 1 of the auxiliary request 1 contains both Mg and Ba in alternative (1). Such a composition is disclosed in Example 9 of Table 2 in the patent in suit.

As pointed out by the appellant in the patent in suit, in particular in Table 2, there is no example of a superconductive oxide material which substantially consists of a single phase ABiCuO, where A is either

a mixture of Ca, Sr and Mg (thus without Ba) or

a mixture of Ca, Sr and Ba, (thus without Mg)

and having the further properties mentioned in the claim.

It was also contended by the appellant in the statement setting out the grounds of appeal that it was known in the art that amounts of Mg and Ba as substituents of Sr and Ca have a negative effect on the high temperature properties and can thus lead to materials which show no supraconductivity. Moreover, according to the appellant, it has not been possible till to date to produce a high temperature ABiCuO single phase 322 superconductive material containing either Mg or Ba.

The appellant submitted in connection with the above Example 9, which is a Sr/Ca/Ba/Mg/Bi/Cu composition in the proportion 1.0/1.0/0.5/0.5/2/2, that even a minimal amount of Mg was known to have detrimental effect on the high temperature superconductive properties. It was therefore contested that it was possible to produce a substantially single phase high temperature superconductive material containing a relatively high amount of Mg as reported in Example 9. In the event that the Board considered it necessary, the appellant would provide a published document supporting his contention.

The question of feasibility of the ABiCu single phase composition containing Mg or Ba was raised by the appellant at the beginning of the appeal proceedings. However, the respondent, apart from stating that such a composition in Example 9 of the patent in suit was produced, did not make any further submissions refuting the allegations of lack of feasibility or reproducibility of the composition.

Also, at the oral proceedings, the respondent, when asked by the Board whether he was aware of any published document reporting a single phase ABiCuO high temperature superconductor containing Mg or Ba, stated that he was not aware of such a document.

In view of the above, the Board is persuaded by the appellant's arguments and concludes that the composition of Example 9 corresponds to an isolated unconfirmed result which has not been reproduced in the art following the ceramic method disclosed in the patent in suit.

Therefore, the Board concludes that the invention as defined in claim 1 of the main or auxiliary request 1 is not sufficiently disclosed (Article 100(b) and 83 EPC).

4. Auxiliary request 2

4.1. Formal requirements

There were no objections by the appellant under Article 84 EPC, Article 123(2) EPC or Article 123(3) EPC against claim 1.

It is to be noted that claim 2 is identical with claim 2 of the text of the European patent application maintained by the decision of the opposition division.

The Board is also satisfied that claim 1 as amended is clear (Article 84 EPC) and complies with Article 123(2) and 123(3) EPC.

4.2. Sufficiency of disclosure

As to the objection under Article 100(b) EPC, the question which needs to be considered is whether taking into account the information provided in the patent in suit and the common general knowledge in the field of ceramic oxide superconductive materials, it would have been possible for a person skilled in the art to obtain a superconductive oxide material as set out in claim 1.

The only information in the patent in suit regarding the manufacture of the superconductive oxide material in question is provided in the two paragraphs preceding Table 2. It follows from this disclosure that for Example 1 of Table 2, a mixture of oxides of Sr, Ca, Bi and Cu was formed so as to give atomic ratio A/Bi/Cu of 3/2/2, the oxides were thoroughly mixed, calcined at 800 to 850 C, crushed, formed and finally sintered at 850 C. In the paragraphs following Table 2, it is further disclosed that compositions 1 to 5, 9 and 10 had a transition temperature in the range of 80 to 85 K and that in case of Example 1 X-ray analysis confirmed the presence of a single crystalline phase with the A/Bi/Cu ratio of 3/2/2.

With regard to the issue of sufficiency of disclosure, the Board accepts the submissions of the respondent (see item IX above) that at the priority date of the patent in suit, the ceramic method was well known in the art for the manufacture of ceramic oxides including the known high temperature superconductive oxides. Consequently, once the skilled person was informed of the formation of a single phase of A/Bi/Cu in the ratio 3/2/2, as in the patent in suit, it was within his routine expertise to adjust various process parameters such as cooling rate, oxygen content, etc..., to reproduce the high temperature superconductive oxide as claimed. This view is supported by the disclosure in document E17 which was published on 1 June 1988, only four months after the priority date of the patent in suit. It follows from the disclosure on page 9382, last paragraph of document E17 that a single phase compound is formed at the composition Bi4Sr3Ca3Cu4Oy (4-3-3-4), ie having A/Bi/Cu ratio of 3/2/2, using a ceramic method similar to the one employed in the patent in suit. Although the lower limit (855 C) of the sintering temperature range (865 C ± 10 C) reported in the document for the formation of the single phase is 5 C higher than the sintering temperature of 850 C employed in the patent in suit, the narrow temperature range in the Board's view cannot be regarded as the necessary requirement. This, as pointed out by the respondent, follows from the disclosure in document E14, which was published after the publication of document E17, wherein it is reported that a single phase compound Bi-Sr-Ca-Cu-O having a A/Bi/Cu ratio of 3/2/2 is formed when the sintering was carried out at 1108 K (835 C) and 1113 K (840 C) (see Table 3, compositions in lines 6 and 7).

The appellant has also referred to the arguments and the results of comparative measurements in his letter dated 23 August 1997 during the opposition proceedings; in particular, for the third example, which corresponds to Example 1 of Table 2 of the patent in suit, with Bi Sr Ca Cu O (BSSCO) with proportions 2 / 1.5 /1.5 / 2, the superconductor is shown as presenting no definite single phase structure and as having a Tc of mainly 77 K, ie under the 80 K required by claim 1 in dispute.

However, as convincingly argued by the respondent, the duration of the heat treatments mentioned in the comparative measurement are in hours, whereas durations in days are generally known to the skilled person (see for instance the cited examples and examples of similar compositions in Table 3 of document E14). Therefore, the results of the comparative measurements are not conclusive and thus not clearly in contradiction to the findings of the patent in suit.

The appellant has also pointed out that although Example 1 in the priority document relevant for 3/2/2 materials, ie, No. 26130/88, is identical with Example 1 of Table 2 of the patent in suit, there is however in the same priority document another example, ie, Example 7, which is disclosed as Example 1 having regard to composition and preparation, but with no single phase of the obtained material; thus, there is a doubt, whether the invention can be carried out in a repetitive way.

The following is to be noted In this respect:

One of the inventors, Dr. Kugiyima, was asked by the Board at the oral proceedings for clarification of this point and stated that Example 7 of the Table of this priority document was wrong and its inclusion was an obvious mistake. This example was therefore not contained in the European application as filed.

The Board finds that this is a plausible explanation so that the above inconsistency cannot be regarded as indicative of nonreproducibility of Example 1 of Table 2.

In any case according to document E14 (see Table 3) materials of the same type as Example 1 have been prepared, so that the appellant's argument is not considered as convincing.

The appellant has also objected that the patent in suit does not disclose the exact formula of the obtained materials, in particular the concentration of oxygen, or the X-ray parameters of said materials. However, as explained by the respondent, the disclosure of the lattice constants in the patent is correct, and the lattice constants a, b and c are close to the values given in documents E12 and E14. Also, the patent specification (cf. page 5, lines 26 to 30) explains how the values a = 1.53 and b = c = 2.29 are obtained. As regards the oxygen content, it was stated by the respondent that sintering was carried out in the air, as is common in the ceramic method.

Thus, notwithstanding the fact that the preparation of the claimed materials was not easy, the skilled person, taking into account the information in the patent in suit and his general knowledge, was in a position to prepare materials of this type without undue burden (see the decision T 409/91, OJ EPO 1994, 653, in particular point 3.5 of the reasons; see also the decision T 435/91, OJ EPO 1995, 188, points 2.2 to 2.2.3. and 4.1 to 4.2).

Consequently, the Board concludes that the invention according to claim 1 of the auxiliary request 2 is sufficiently disclosed in the sense of Article 100(b) and 83 EPC.

4.3. Novelty

4.3.1. For determining the extent of the state of the art in the sense of Article 54(2) EPC, it is necessary to consider whether the patent in suit is entitled to the claimed priority.

The priority document 26130/88 discloses in the first example of the Table a material with identical composition and identical results and properties as Example 1 of Table 2 of the patent in suit. Thus, the auxiliary request 2 represents the same invention as in the priority document. Moreover, since the information in the priority document 26130/88 is in substance very close to the auxiliary request 2 and since as set forth above this request has been found to disclose the invention in a manner sufficiently clear and complete for it to be carried out by a person skilled in the art, the disclosure in the priority document is considered as being enabling.

Therefore, the Board concludes that the auxiliary request 2 is entitled to the priority of, in particular, the priority document 26130/88 (Article 87(1) EPC).

The documents E13 to E17 published after the priority date of the patent in suit are therefore not comprised in the state of the art according to Article 54(2) EPC.

4.3.2. In the opinion of the Board, none of the prior art documents in the sense of Article 54(2) EPC discloses or suggests a material according to claim 1 of the auxiliary request 2, so that the subject-matter of claim 1 is new. This has not been disputed by the appellant.

It is to be noted that the appellant had submitted that the subject-matter of claim 2 was not new in the sense of Article 54(3) EPC having regard to the content of document E5, which is a European patent application claiming a priority anterior to the priority of the patent in suit, in particular having regard to Example 1 of Table 1 thereof, which is identical to Example 3 of Table 3 of the patent in suit. However, since according to the auxiliary request 2 none of the examples of Table 3 of the patent in suit falls within the scope of the invention, and since moreover document E5 in particular does not disclose a multi-layered superconductive oxide material in accordance with claim 2, this claim is new.

4.4. Inventive step

As mentioned above, document E5 belongs to the state of the art according to Article 54(3) EPC. This document is therefore not relevant for the consideration of inventive step.

Document E3 discloses a high temperature superconductive oxide having Bi-Sr-Ca-Cu2Ox composition which comprises at least two high temperature superconducting phases. There is no suggestion in any of the remaining cited prior art documents regarding a substantially single phase ABiCuO composition as set out in claim 1 of the patent in suit, so that it was not obvious to the skilled person to arrive at the claimed invention in view of the cited prior art.

4.5. For the foregoing reasons, the Board concludes that claims 1 and 2 are new in the sense of Article 54 EPC and that they involve an inventive step in the sense of Article 56 EPC.