Yes you can. The Glorified Allah commands:
“If the debtor is in a difficulty, grant him time until easiness. But donating (و ان تصدقوا : giving as alms or zakat) is better for you, if you knew.” (Al-Baqarah/ The Cow 2:280)
The word mentioned in the verse is of the root “sadaqa”. The Glorified Allah uses a similar word of the same root in the verse that determines the receivers of zakat.
“Zakat expenditures are for the poor, the desperate, those employed to collect Zakat and those to warm their hearts (to Islam); and are used for freeing captives, for those in debt, for the cause of Allah and for the travelers. This is an obligation by Allah. Allah is All-Knowing and the Wise.” (At-Tawbah/ The Repentance 9:60)
If we associate the two verses, we can understand that receivables can be given as zakat.